Mechanical desk stand for cylindrical slide rules



oct. 21, A1941.

c. lsUT'roN 2,259,786

MECHANIDAL DESK STAND FOR GYLINDRICAL SLIDE RULES Filed Dec. 14,' 1938 s sheets-sheet 1 C. SUTTON Oct. 21, 1941.

MECHANICAL DESK STAND FOR GYLINDRICAL SLIDE RULES Filed Deo. 14, 1938 3 Sheets-Sheet 2 C. SUTTON Oct. 21, 1941.

MECHANICAL DESK STAND FOR CYLINDRICAL SLIDE RULES Filed Dec. 141, 1938 3 Sheets-Sheet y3 5 w 5M 9 oNo/. mdd/...L n F w 3 3 w. M H /1 H 7 WK 5 Um fw w 9 H #j 7W .l 4 H F Patented Oct. 21, 1941 MECHANICAL DESK STND FOR CYLINDRI- CAL SLIDE RULES Coleman Sutton, Alhambra, Calif. Application December 14, 1938, Serial No. 245,662 10 Claims. (Cl. 23579.5),

Thisinvention relates to improvements in desk stands, and has for an object yto provide a desk stand for the support of cylindrical slide rules of the type described in application Serial No.-

125,875 filed February 15, 1937.

A further object is to provide a desk stand 'upon which such a cylindrical slide rule may be readily secured for operation therewith. Y

A further object is to provide a desk stand from which ,the cylindrical slide rule may be readily removed for independent operation when desired, as when making or checking calculations on the slide rule in the field; or when the top' of a desk, table, or similar fiat surface may not be readily available; or under other circumstances in which it may be preferred to operate the slide rule inin connection v dependently of the desk stand.

A further object is to provide a desk stand such that the cylindrical slide rule can be conveniently and rapidly operated thereon with the right hand only. thus leaving the left hand of the operator free for other purposes, as for holding a telephone receiver, or for handling trigonometrical tables, etc. This permits the direct transfer4 of figures received over the telephone or selected from mathematical tables, or other-l wise, to corresponding values upon the scales of the cylindrical slide rule with less likelihood of error and with a minimum loss of time. Thus the figures to be used may be selected from tables, maps, drawings, etc.,-and while'being pointed out with the index finger of the left hand these figures caribe transferred Vto the slide rule with the right hand only. All calculations gan then be made with the right hand only, leaving the leftv hand free to retain the place in the mathematical table, or on the map, etc. Calculations can therefore be made onv the cylindrical slidel rule .with'the aid of the desk stand with y, less likelihood of error in transferring the figures to the 'slide rule, and with greater speed than has heretofore been customary in the operation of slide rules. l

` A further object is to provide a desk stand upon which the cylindrical-slide rule can be releasably clamped in an operating position.

A further object is to pro'vide means whereby the scale yoperatingelements of the slide rule may be releasably and individually heldin set positions. A further object is to provide, in a preferred embodiment of my invention, a braking system j especially devised to be operated by means of 'a `single controlling element foreach brake, which easily turned, in order to hold the drum locked in stopped position; and (3) the brake shoe may be either ,gradually released fromthe drum or may be allowed to spring instantly into its fully released position. By providing a pair of brakes that can be either rapidly applied, locked, or instantaneously released as desired, by. means of but a single controlling element for each brake, the slide rule can be operated upon the desk stand more rapidly and conveniently than can otherwise be done.

' A further object is to provide, in a preferred embodiment of my invention, a brake in which the brake shoe can rotate slightly so as to insurel its concentricity with the brake drum when the brake is set, thus automatically compelling the whole frictiohal braking surface of the brake shoe to come into contatwith the brake drum.

`Affurther object is -to provide a desk stand such that a magnifying glass maybe readily mounted and'adjusted thereon to facilitate reading vthe scales of the slide rule.

With they foregoing and other objects in view after fully described and claimed.

In the accompanying drawings forming part of this specification and illustrating a preferred embodiment of my inventionz' Figure 1 is a perspective view showing'the slide I rule secured in operating position upony the desk stand, with the keys for actuating the brake shoes shown in locked position. w

Figure 2 is a front elevation of a portion of the magnifying glass held by a' supporting standard and appurtenances.

Figure 3 is a perspective view showing the desk stand with the slide ruleremoved therefrom, with the keys in released position, and with the clamp in open position.

Figure 4 is a detail side elevation looking toward the left-hand side of the desk stand, showing the lever which controls the clamp held in its closed position by means of `a spring catch;

Figure 5 is a detail side 'elevation looking toward the right-hand side of the desk stand, showing the mechanism operating the 'brake shoes.

Figure 6 is a detail sectional view takenv on' the line 6-6 of Figure 5 showing parts in elevation.

Referring now to the drawings, in which like characters of reference designate similar parts in the various views, |l designates a base supported upon pedestals |0| preferably four in number secured to said base by screws |02.

A rectangular block |03, the upper surface of which forms a concave bed as shown in Fig. 3, is centrally located upon the said base |00 and is secured thereto by screws passed upward through the base and into the said block. The upper right-hand edge portion |04 of said block is recessed as shown to accommodate the screws -20 of the slide rule.

Two supporting standards |05, best shown in Fig. 3, are mounted upon the base |00 in rear of the rectangular block |03 and are likewise secured by screws passed upward through the base and into said supporting standards. A rotary shaft |06 is supported in bearings provided in the upper portions of said standards, as shown in Fig. 3. A curved clamp |01 is rmly secured to the shaft |06 by welding or otherwise. A short nat bar |08 is secured by rivets |09 to the back of said clamp and extends beyond the right-hand edge thereof. The outer portion of said bar |00 strikes against the upper rear portion of the right-hand supporting standard when the clamp is opened, as shown in Fig. 3, and thereby stops the clamp from turning too far backward for convenience.

As best shown in Fig. 3, two arcuate shoes ||0 are carried by respective arms which comprise outwardly extending portions of the aforesaid clamp |01, said shoes being secured to said arms by screws ||2 as shown in the closed position of said clamp illustrated in Fig. 1, there being preferably two of said screws securing 'each shoe.

A lever |3 having its free end portion widened to form a handle, is provided for turning the shaft |06 to swing the clamp |01 to its open or closed position. The open position of said lever is shown in Fig. 3, and itsclosed position isshown in Fig. 4. Said lever is secured to the shaft |00 by a screw ||4 as shown in Fig.,4. A collar l5 is Asecured by ascrew ||6 to the shaft |00, as shown in Fig. 3, said collar being provided to prevent the shaft from slipping out of place longitudinally. The lever ||3 may'be returned to its locked position after the slide rule has been removed, in order to hold the clamp |01 and to diminish the amount of space occupied by the desk stand.

As shown in Fig. fi. the lever ||3 is locked in its closed position by a leaf spring ||1 supported upon a small rectangular block l0 mounted upon the aforesaid base |00, said block and said leaf spring being held in place by two bolts 'I l0 passed through them and through the/ base |00. A screw partially inserted into the standard |05, as shown in Fig. 4, limits the upward action oi' the leaf spring ||1 and thereby prevents it 'from dangling loosely whenthe lever |I3 is in -its open position.

Although Fig. 4 ment for locking the it is to be understood that other means for releasably mounting the clamp |01, an'd that other forms of locking mechanisms or spring catches may be resorted to forthis purpose, if desired, within the scope of the appended claims. In fact, in another embodiment o f my invention I provide the clamp |01 mounted upon a vertical illustrates a preferred arrangescale operating elements of the lever controlling the clamp,

' Fig. 3.

round rod adapted to be inserted intb a short standard which may be attachd to the base in rear of the concave bed, in lieu of the standards |05, the said vertical rod being releasably secured within its said supporting standard by means of a thumbscrew. In this case in order to release the clamp it is only necessary to unscrew the thumbscrew and lift the clamp, which may then be removed entirely with its supporting rod, or may be swung to the rear on the vertical axis of said rod.

For releasably Aand individually holding the slide rule vin set positions, two keys designated and 2 respectively are pivoted on the end of respective bars |2| by screw shafts |22. The lower end portions of said keys releasably hook into a recessed portion of an irregularly shaped member |23 mounted on the aforesaid base |00 by means of bolts |24 as shown in Fig. 5, there being preferably two of said' bolts longitudinally disposed with respect to the said irregularly shaped member |23.

Protruding portions |25 formed on the aforesaid keys extend over the upper surfaces of their respective supporting bars |2| and thereby stop the keys from being rotated too far in that direction when being released. Coil springs |26 are connected between the keys and their respective bars |2| by hooking the ends of said coil springs in holes provided in the keys and in their respective bars, as shown.

The bars |2| operate through vertical slots |21 provided in a bracket |28 mounted on the base |00 by means of bolts |29 shown in Fig. Y5, there being preferably two of said bolts longitudinally disposed with respect to said bracket. The upper surfaces of the two slots |21 serve to stop their respective bars |2| and thereby prevent the keys from rising too high when released, as shown in In order that it may not be too difiicult to push the keys down into their respective locked positions, the action of the bars |2| may be made slightly resilient by cutting them in two and inserting within each of them a leafspring |30 secured by rivets |3| I ever, this may not be necessary if the parts are made with suilicient accuracy togive correct braking pressure without resilient action,`o1 if the bars |2| are made of such size and material as to provide within themselves suiilcient resiliency while retaining sufilcient strength.

'Ihe said bars |2| are pivoted intermediate their ends upon a shaft |32 carried by a hinge |33 which is secured to the aforesaid base |00 by a bolt |34 as best shown in Figs. 1 and 3. Said bars |2| are confined in their respective positions upon the shaft |32 by three collars |35, the middle one of which is secured to the shaft |32 by a screw |36 to prevent the shaft from slipping out of place longitudinally. f

As best shown in Figs. 5 and 6, two brake shoes |31 are pivoted upon the respective rear ends of the bars |2| by means of hinge lugs |38 which are mounted upon respective screw shafts |30 that pass through the rear end portions of the bars |2| and are free to turn therein, said screw shafts |39 being secured by threaded holes in the hinge lugs |38-, The bars |2| vare centrally confined within 'their respective hinge lugs |38 by washers |40 as shown in Fig. 6. The two brake shoes |31 are secured to their respective hinges |30 by' screws |4| as shown in Fig. 6, there being preferably two of said screws securing each brake shoe. Two round spacer rods |42 as best shown in Fig. 5. How- Y,brake shoes. `upper portion of each leafspring whereby each drawn too close together and thereby binding against the rear end portions'of their respective bars |2| when the screw shafts |30 are drawn tight.

Two coil springs I 43, best shown in Fig. 6, are

`hooked over their respective spacer rods |42 and extend downward through respective holes- |44 provided in the aforesaid base |00. The'lower ends of said coil springs hook into respective holes provided in d piste |45 which is secured below the -base between two nuts on'a bolt |45 as shown in Figs. 5 and 6. Said coil springs |43 exert outward radial tension on their respective hinge lugs |38, thereby keeping the arcuate surfaces of the brake shoes |31 substantially concentric with the scale operating rings of the slide rule, andimpelling the instant release of said brake shoes from the operating rings of the slide rule when the aforesaid keys designated I and 2 respectively are unhooked.

It will be noted that the amount of tension in the coil springs |43, and hence'the maximum amount of radial thrust that can be exerted by the brake shoes, may be increasedl orv decreased by changing the set position of the plate |45 upon the bolt |46. As will be explained more fully hereinafter, `the maximum amount of radial thrust that is exerted by the brake shoe actuated by key No. 2 must be somewhat more carefully controlled, as by the adjustable plate |45, than need be that exerted by the other brake shoew" By providing but one adjustable plate |45 for attaching both springs |43, the tension in both springs is automaticallyequalized regardless 0f the set position of said plate, thus at all times providing for a practically uniform pressure, yor touch, necessary upon either key toactuate its brake shoe, However. nothing stated herein is to be construed as prohibiting the use of separate means for individually adJusting the tension in 'the two springs |43, should this be desired, within the scope of the appended claims, as by providingfor example, a separate bolt and ad- Justable plate for each spring. l

In fact, in 'another embodiment of my invention' I provide the two brake shoes suspended yvertically in front of the scale operating rings of the slide rule, upon the freeupper ends of individual leaf-springs'attached at their lower ends to the lower part of a standard mounted on the base of the desk stand, the top of said standard being at 'approximately the same height as the In thisV case'I provide ahook on the spring can be pulled back individually land hooked to the supporting standard to hold its brake shoe released from the slide rule. Thus in the operation of this embodiment of my invention the lower portion of said brake shoes are automatically actuated and heldl against the scale operating rings of the slide rule .by means of respective leaf springs. andare released and `held in released position by means of respective hooks attached to said leaf springs, said hooks being adapted torelea'sably snap into respective catches provided therefor upon a supj porting lstandardmounted. on the 'base of the desk stand. r v

In this said embodiment of my invention wherein thebrake shoes are suspended vertically in front of the scale operating rings of the slide rule, the rectangular block |03 is not necessary the base |00, or other or turned on the vertical axis Since it has already been explained herein how.

means otherV than that illustrated may be provided for releasably mounting the clamp |01, and since the brake shoes may be suspended vertically by other means as Well as horizontally as illustrated. and since the rectangular block |03 as illustrated may be entirely dispensed with in certain arrangements of the device, it is ther fore thought to be impractical to attempt to describe and illustrate all of the possible arrangements and forms of the desk stand in detail herein, it being understood however that various modications in the preferred embodiment as described and illustratedmay be resor d to within the scope of the appended claims wit out departthe slide rule are preferably lined with felt or other cushioning material |41 to prevent marring the instrument and -to assist in holding it securely when in operation on the desk stand.

A magnifying glass |48, a portion ofwhich i s illustrated in Fig. 2, is secured by a bracket |49 o` a horizontal round rod |50 which passes through a hole in the vupperportion of a vertical round rod |5|. Abovethe said hole, the vertical rod `|5| is split vertically on a plane passing through the horizontal rod |50. A thumbscrew |52 passes at a right angle through the said split portion of the vertical rod |5| and when tightened clamps the said vertical and horizontal rods together.

The vertical rod |5| extends downward into a supporting standard |53 and is secured therein by a thumbscrew |54, as shown in Fig. 2. The

constitutesra horizontal projecting portion thereof carrying a thumbscrew |55 extending through approximately the upper half of said projecting portion and into a slot |56 provided therein,.as also shown in Fig, 2.`

Whenuse of the magnifying glass is desired, the supporting standard |53 is slipped over the left-hand edgeportion of the aforementioned base |00 of the desk stand by means ofthe slot |56, 'and is. clamped onto .the said base at anyv preferred distance means of the thumbscrew |55. A rubber-tip may be provided on the lower end of said thumbscrew |55- toprevent it from marring the surface of means can be employed for this purpose, if desired.

By loosening th thumbscrew fying glass may then beadjusted up or down, of the rod |5|, and then held by retightening the thumbscrew |54.- Then by loosening the thumbscrew |52 the magnifying glass may be adjusted horizontally to the right or to the left, or turned upon the horizontal axis of the rod |50, and then held by. again tighteningthe 'thumbscrew' |52. The

magnifying glass is thus universally adjustable to to supportthe slide rule above horizontally sus- .supporting standard |53 infront of the slide rule by 54, the magniaway in Fig. 2' for the sake of v portlonof the scales on A stand with number or subdivision on clarity in the drawings, the magnifying glass actually being of sufcient length ,to extend completely across all of the scales on the slide rule. The magnifying glass is preferably not framed, for a frame around the glass .would obscure a the slide rule. The slide rule may be placed upon or removed from the desk stand without disturbing the position of the magnifying glass thereon.

Use of the magnifying glass greatly facilitates reading the scales on the slide rule, but its use is not strictly necessary for the successful operation of the slide rule upon the desk stand. No claims therefore are appended hereto for the magnifying glass and its appurtenances, as illustrated in Fig. 2 for it is believed that such do not constitute a true combination with the desk stand and do not represent invention per se.

In order to operate the cylindrical slide rule upon the desk stand, the lever |I3 is first unlocked by pushing down on the free end portion of the' leaf spring shown in Fig. 4. The lever is then swung forward, opening the clamp |01, and the keys designated I and 2 respectively are released, as shown in Fig. 3.

The slide rule is then placed upon the desk itsA transparent cover I1 resting in the aforementioned concave bed which forms the upper surface of the rectangular block |03, and is turned if necessary to bring one of the hair lines 22 to a lconvenient position for the operator. If the magnifying glass |48 is to be used, the hair line 22 should be set to appear at about the middle of the magnifying glass. The slide rule is then pushed gently toward the left until it is stopped by the flange 45 on its transparent cover striking the right-hand side of the bed. The clamp |01 is then closed by pushing down the lever ||3 until said lever is-automatically locked by the leaf spring ||1 as shown in Fig. 4. The shoes on the clamp are thereby closed .tightly against the transparent cover I1 of the slide rule. as-shown in Fig. l, and the slide rule is then ready for operation.

With the slide rule clamped in position as described, .the rotary transparent cover |1 thereon is no longer free to turn, and the hair line index 22 therefore remains fixed in its selected position. However, the three scale-bearing elements on the slide rule may be readily turned within the transparent cover by `means of their external controlling elements at the right-hand end portion of the slide rule, and therefore any number or subdivision on Aany scale'may be readily turned to coincidence with the hair line index. Since the operation of the slide rule also. requires that a one scale be brought into alignment on the hair line index with another number`or subdivision on another scale, and since this is` to be done with one hand only in this case. the hereinbefore described keys designated and 2 respectively are provided to lock certain of the scales in position whilev others of the scales are being turned.

Thus if .either one of the said keys be .pushed downward itl will cause its corresponding supporting bar |2| to turn upon the shaft |32 with' the corresponding 4brake shoe resultant rise of |31 which thereupon frictionally engages the periphery of the corresponding controlling ring 34 or 35, as the casemay be, of the slide rule,

.and thereby prevents the said ring from turning.

Hence the relatively fixed scales on the slide rule may be locked in position by key No. while ||1 in rear of the lever, as

thethumb of the right whereupon the coilsprings y .rotating while at the same the scales.

with key No. 2 released, the rotary scales may be turned by means of the ring 34 or the knob 3B. Likewise, the rotary scales may be locked by key No. 2, while with key No. released, the fixed scales may be turned by means of the ring 35. And further, with both keys released, all of the scales may be turned at once by means of the ring 35.

It will be noted that the brake shoe actuated by key No. 2 extends over a greater length of circular arc than does that of the brake shoe actuated by key No.' This has been done in View of the fact that the rin'g 34 of the slide rule, which is to be stopped from turning by means of key No. 2, is suspended upon frictional rollers within the instrument, and. if too much upward pressure is exerted by the brake shoe in stopping the ring 34, this external upward pressure may overcome that of the frictional rollers within, with the result that the said ring 34 may be pushed upward and bind against the interior supporting cylinder of the slide rule, thereby stopping the entire slide rule from turning. By providing its brake shoe with a sufficiently large frictional surface however, the upward pressure of the brake shoemay be reduced, so .that the ring 34 can be held in position without internal binding, thus permitting rotation of the relatively iixed scales while the rotary scales are held stationary by means of the brake shoe actuated by key' No. 2f: However, nothing stated herein is to be construed as restricting the relative size of either brake shoe, since the thrust thereof may also be regulated as hereinbefore described by adjusting the tension in the coil springs |43.

In order to lock either of the two keys and thereby set their brakes, it is only necessary to push the keys down, whereupon the coil springs |26 automatically snap them into their locked positions; and in order to release the keys it is only necessary to push against the near edge of their tops, thereby unhooking their lower ends, |43 pull down the brake shoes and cause the Akeys to rise. Thus either key may bepushed down and locked with hand, or if locked may be pushed against with the same thumb and released, in either case but very slightly removing the 'right hand from the controlling elements of the slide rule. Hence virtually no time is lost ln the process of locking or releasing the keys, and with but little practice the operator can learn to do this without stopping to look at thev keys.

It will here be noted that in the operation of the slide rule when detached from the desk stand, it is necessary for the operator to use both hands when he'must hold the hair line index 22 from Ttime he must rotate In that case he must-hold the flange 45 stationary with his right hand while he rotates the scales with his left hand by means of the flangeat' the left of the scales. When the slide rule is clamped on the desk stand however, use of theleft hand is no longer necessary for this purposel as the clampv |01 then prevents the hair line 22 from rotating, and the scales can then be rotated with the right hand only, as hereinbefore described. Thus ythe clamp |01 not only holds the entire slide ruleA -in position for the brakes, but its action in'holding the hair line index from automatically rotating when the scales are turned is necessary, together with the brakes, to accomplish the purpose of making possible the operation of the entire slide rule with the right hand aana'rse and then locked by key No. l, and while the fixed scales are thus being held the rotary scale-bearing element in the middle thereof may be turned divisions therewith, whereupon said key No. l may be released and all the scale-bearing elements turned together for a final reading or a new setting on the hair line index. Hence key No. 2 and the parts operated always be considered strictly necessary and may not be provided, but may be or desirable to first set and hold the rotary scales in position before setting the fixed scales.

- It is believed that the key and brake shoe method described herein represents improvement in braking devices whereby a brakev may be set, locked, and released more quickly and conveniently than has heretofore been customary in such devices, However, in this case the braking arrangement illustrated represents primarily a preferred embodiment of one of the features of my invention and may be modified if desired within thereby may not provided for use in cases in whichit may be thought more practical drical slide rule upon the aforesaid concave thereby prevent rotation of the said cursor,

' to they required alignment of its numbers or subi,

h/aft supported by said standards, an A arcuate member'mounted upon said shaft betweenA said standards, a'portion of said shaft extending beyond one of said standards, and a handle on 'the extended portion of said shaft for rotating the yshaft to open and close said clamp.

2. brake including a base, a supporting member a' tached to said base, a bar pivoted on said supporting member, a key pivoted on said vbar for actuating said brake, a portion of said key forming a hook, a catch on the aforesaid basefor.

receiving said hook, and a spring connecting said vkey with the aforesaid bar for snapping saidv hook into said catch to hold said brake in set 3. A Ibrake including -a base, a'supporting member* attachedA .to said base,A a bar pivoted intermediate its ends on said supporting member. a

. keycpivoted on an end portion of, said bar for actuating said brake, avportion off saidkey forming a hook, a catch ony the aforesaid base yfor receiving said hook, a spring connecting said key with the aforesaid bar for vsnapping said hook into l said catch to hold said brake in set position, a

brake shoe pivoted on the other end portion of the vaforesaid bar, anda spring connecting said brake shoe to the aforesaidbase for holding the brake shoe in inoperative position an'd to impel the release of said brake when the aforesaid key is unhooked. l

f4r. A desk stand including a base, a concave L on the extendedportion of said shaft for rotating the shaft to clamp the rotary cursor of a cylinbed upon said base, a pair ofjstandards upon l -to engage the aforesaid cylindrical slide rule in such manner as to prevent rotation of its relatively xed scales when the aforesaid cursor of the said slide rule is clamped upon the aforesaid concave bed as hereinbefore described, a spring connecting the said brake shoe to the aforesaid base for holding the brake shoe in inoperative position and to impel therelease of saidl brake shoe, a key pivoted on the other end portion of the aforesaid bar for actuating said brake shoe, a portion of said key forming a hook', a catch on the aforesaid base for receiving said. hook, and a spring connecting said key with the aforesaid bar for snapping said hook into said .catch to hold the aforesaid brake shoe in set position, a base supporting said clamp, and a brake mounted upon said base adapted vto re- .leasably hold a scale bearing element of said slide rule in set positions when the cursor of said sliderule is held in fixed position by the aforesaid clamp, so that the said slide rule canbe operated with only one hand upon the desk stand herein claimed.

6. A brake including a brake drum having a cylindrical periphery, a brake shoe, having an arcuate surface adapted to .engage the periphery of said drum for applying said brake,.and a lever pivotally supporting said brake shoe to allow said brake shoeto rotate sumciently thereon to automatically insure concentricity Vbetween the arcuate surface of said brake shoe and the periphery of saidbrake drum when the aforesaid brake is applied.

*1. A brakeincluding abrale drum having a cylindrical'periphery, a brake shoe having any arcuate surface adapted to engage the periphery of said drum for applying saidlbrakea lever pivotally supporting said brake shoe to allow said brake shoe to rotate suiiiciently thereon to automatically insure concentricity 4between the arcuate surface oi said brake shoe and the periphery of said brake drum when the aforesaid brake is applied, and a spring connected to said brake shoe adapted to'hold the arcuate surfaceof said .brake shoe substantially concentric with the periphery of saidbrake drum .when the said 'brake brake shoe to rotate Asuiiiciently thereon to auto-v matically insure concentricity between the arcuate surface of said brake shoe and the periphery of said brake drum when the aforesaid brake is applied, a member pivotally supporting said lever, a base supporting said member, and an elastic connection between said base and said brake shoe forholding the arcuate surface of said brake shoe substantially concentric with the periphery of .bers mounted upon vsaid brake drumI when the said brake is in inoperative position.

9. A brake including a base, supporting mem,

said base, a'brake drum having a cylindrical periphery rotatably supported by said supporting members, a pivotal member mounted upon said base, a lever pivoted on said pivotal member, and a. brake shoe having an arcuate surface adapted to engage the periphery of said brake drum for applying saidv brake pivoted on said leverl so as to rotate sufficiently thereon to automatically insure concentricity between the arcuate surface of said brake shoe and the periphery of said brake drum when the brake is applied.

10. A brake including a base, supporting members mounted upon said base, a brake drum having a cylindrical periphery rotatably supported by said supporting members, a pivotal member mounted upon said base, a lever pivoted on said pivotal member, a brake shoe having an arcuate surface adapted to engage the .periphery of said brake drum for applying said brake pivoted on said lever so as to rotate sufficiently thereon to automatically insure concentricity between the arcuate surface of said brake shoe and the periphery of said `brake drum when the brake is applied, and an elastic connection between said brake shoe and the aforesaid base for holding the arcuate surface of said brake shoe substantially concentric with the periphery of said brake drum when the said brake is in inoperative position. e

lCOLEMAN SU'I'I'ON. 

